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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"

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<refentry id="glDrawRangeElements">

    <refmeta>

        <refmetainfo>

            <copyright>

                <year>1991-2006</year>

                <holder>Silicon Graphics, Inc.</holder>

            </copyright>

        </refmetainfo>

        <refentrytitle>glDrawRangeElements</refentrytitle>

        <manvolnum>3G</manvolnum>

    </refmeta>

    <refnamediv>

        <refname>glDrawRangeElements</refname>

        <refpurpose>render primitives from array data</refpurpose>

    </refnamediv>

    <refsynopsisdiv><title>C Specification</title>

        <funcsynopsis>

            <funcprototype>

                <funcdef>void <function>glDrawRangeElements</function></funcdef>

                <paramdef>GLenum <parameter>mode</parameter></paramdef>

                <paramdef>GLuint <parameter>start</parameter></paramdef>

                <paramdef>GLuint <parameter>end</parameter></paramdef>

                <paramdef>GLsizei <parameter>count</parameter></paramdef>

                <paramdef>GLenum <parameter>type</parameter></paramdef>

                <paramdef>const GLvoid * <parameter>indices</parameter></paramdef>

            </funcprototype>

        </funcsynopsis>

    </refsynopsisdiv>

    <!-- eqn: ignoring delim $$ -->

    <refsect1 id="parameters"><title>Parameters</title>

        <variablelist>

        <varlistentry>

            <term><parameter>mode</parameter></term>

            <listitem>

                <para>

                    Specifies what kind of primitives to render.

                    Symbolic constants

                    <constant>GL_POINTS</constant>,

                    <constant>GL_LINE_STRIP</constant>,

                    <constant>GL_LINE_LOOP</constant>,

                    <constant>GL_LINES</constant>,

                    <constant>GL_TRIANGLE_STRIP</constant>,

                    <constant>GL_TRIANGLE_FAN</constant>,

                    <constant>GL_TRIANGLES</constant>,

                    <constant>GL_QUAD_STRIP</constant>,

                    <constant>GL_QUADS</constant>,

                    and <constant>GL_POLYGON</constant> are accepted.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>start</parameter></term>

            <listitem>

                <para>

                    Specifies the minimum array index contained in <parameter>indices</parameter>.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>end</parameter></term>

            <listitem>

                <para>

                    Specifies the maximum array index contained in <parameter>indices</parameter>.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>count</parameter></term>

            <listitem>

                <para>

                    Specifies the number of elements to be rendered.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>type</parameter></term>

            <listitem>

                <para>

                    Specifies the type of the values in <parameter>indices</parameter>. Must be one of

                    <constant>GL_UNSIGNED_BYTE</constant>, <constant>GL_UNSIGNED_SHORT</constant>, or

                    <constant>GL_UNSIGNED_INT</constant>.

                </para>

            </listitem>

        </varlistentry>

        <varlistentry>

            <term><parameter>indices</parameter></term>

            <listitem>

                <para>

                    Specifies a pointer to the location where the indices are stored.

                </para>

            </listitem>

        </varlistentry>

        </variablelist>

    </refsect1>

    <refsect1 id="description"><title>Description</title>

        <para>

            <function>glDrawRangeElements</function> is a restricted form of <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>. <parameter>mode</parameter>, <parameter>start</parameter>, <parameter>end</parameter>,

            and <parameter>count</parameter> match the corresponding arguments to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>, with

            the additional constraint that all values in the arrays <parameter>count</parameter> must lie

            between <parameter>start</parameter> and <parameter>end</parameter>, inclusive.

        </para>

        <para>

            Implementations denote recommended maximum amounts of vertex and

            index data,

            which may be queried by calling <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument

            <constant>GL_MAX_ELEMENTS_VERTICES</constant> and <constant>GL_MAX_ELEMENTS_INDICES</constant>.

            If

            <inlineequation><mml:math>

                <!-- eqn: end  -  start  +  1:-->

                <mml:mrow>

                    <mml:mi mathvariant="italic">end</mml:mi>

                    <mml:mo>-</mml:mo>

                    <mml:mi mathvariant="italic">start</mml:mi>

                    <mml:mo>+</mml:mo>

                    <mml:mn>1</mml:mn>

                </mml:mrow>

            </mml:math></inlineequation>

            is greater than the value of

            <constant>GL_MAX_ELEMENTS_VERTICES</constant>, or if <parameter>count</parameter> is greater than the value of

            <constant>GL_MAX_ELEMENTS_INDICES</constant>, then the call may operate at reduced

            performance.  There is no requirement that all vertices in the range

            <inlineequation><mml:math>

                <!-- eqn: [start, end]:-->

                <mml:mfenced open="[" close="]">

                    <mml:mi mathvariant="italic">start</mml:mi>

                    <mml:mi mathvariant="italic">end</mml:mi>

                </mml:mfenced>

            </mml:math></inlineequation>

            be referenced.  However, the implementation may

            partially process unused vertices, reducing performance from what could

            be achieved with an optimal index set.

        </para>

        <para>

            When <function>glDrawRangeElements</function> is called, it uses <parameter>count</parameter> sequential elements from an

            enabled array, starting at <parameter>start</parameter> to construct a sequence of

            geometric primitives. <parameter>mode</parameter> specifies what kind of primitives are

            constructed, and how the array elements construct these primitives. If

            more than one array is enabled, each is used. If

            <constant>GL_VERTEX_ARRAY</constant> is not enabled, no geometric primitives are

            constructed.

        </para>

        <para>

            Vertex attributes that are modified by <function>glDrawRangeElements</function> have an

            unspecified value after <function>glDrawRangeElements</function> returns. For example, if

            <constant>GL_COLOR_ARRAY</constant> is enabled, the value of the current color is

            undefined after <function>glDrawRangeElements</function> executes. Attributes that aren't

            modified maintain their previous values.

        </para>

    </refsect1>

    <refsect1 id="notes"><title>Notes</title>

        <para>

            <function>glDrawRangeElements</function> is available only if the GL version is 1.2 or greater.

        </para>

        <para>

            <function>glDrawRangeElements</function> is included in display lists. If <function>glDrawRangeElements</function> is entered into a

            display list,

            the necessary array data (determined by the array pointers and

            enables) is also

            entered into the display list. Because the array pointers and

            enables are client-side state, their values affect display lists

            when the lists are created, not when the lists are executed.

        </para>

    </refsect1>

    <refsect1 id="errors"><title>Errors</title>

        <para>

            It is an error for indices to lie outside the range

            <inlineequation><mml:math>

                <!-- eqn: [start, end]:-->

                <mml:mfenced open="[" close="]">

                    <mml:mi mathvariant="italic">start</mml:mi>

                    <mml:mi mathvariant="italic">end</mml:mi>

                </mml:mfenced>

            </mml:math></inlineequation>,

            but implementations may not check for this situation. Such indices

            cause implementation-dependent behavior.

        </para>

        <para>

            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not an accepted value.

        </para>

        <para>

            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> is negative.

        </para>

        <para>

            <constant>GL_INVALID_VALUE</constant> is generated if

            <inlineequation><mml:math>

                <!-- eqn: end < start:-->

                <mml:mrow>

                    <mml:mi mathvariant="italic">end</mml:mi>

                    <mml:mo>&lt;</mml:mo>

                    <mml:mi mathvariant="italic">start</mml:mi>

                </mml:mrow>

            </mml:math></inlineequation>.

        </para>

        <para>

            <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an

            enabled array or the element array and the buffer object's data store is currently mapped.

        </para>

        <para>

            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glDrawRangeElements</function> is executed between

            the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.

        </para>

    </refsect1>

    <refsect1 id="associatedgets"><title>Associated Gets</title>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_ELEMENTS_VERTICES</constant>

        </para>

        <para>

            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_ELEMENTS_INDICES</constant>

        </para>

    </refsect1>

    <refsect1 id="seealso"><title>See Also</title>

        <para>

            <citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glColorPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glEdgeFlagPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glGetPointerv</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glIndexPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glInterleavedArrays</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glNormalPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glSecondaryColorPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glTexCoordPointer</refentrytitle></citerefentry>,

            <citerefentry><refentrytitle>glVertexPointer</refentrytitle></citerefentry>

        </para>

    </refsect1>

    <refsect1 id="Copyright"><title>Copyright</title>

        <para>

            Copyright <trademark class="copyright"></trademark> 1991-2006

            Silicon Graphics, Inc. This document is licensed under the SGI

            Free Software B License. For details, see

            <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.

        </para>

    </refsect1>

</refentry>